Punch-retaining assembly



Nov. 4, 1952 o. MUELLER PUNCH-RETAINING ASSEMBLY 3 Sheets- Sheet 2 INVENTOR.

v Mae [Xe/r Filed Dec. 7, 1949 H 772 F/VEVS.

Nov. 4, 1952 o. MUELLER PUNCH-RETAINING ASSEMBLY 3 Sheets-Sheet 3 Filed Dec. 7, 1949 47 w ll R. .5 m M r 53 1 fi w O my 08 M I 1.

Patented Nov. 4, 1952 I UNITED STATES PATENT OFFICE PUN CH-RETAININ G ASSEMBLY Otto Mueller, Dearborn, Mich.

Application December 7, 1949, Serial No. 131,571

15 Claims.

This invention relates broadly to new and useful improvements in punch presses and more particularly to an improved assembly for mounting punches in the punch-carrying plates of such presses.

Punch presses of the type here under consideration are conventionally equipped with a plate which carries one or more punches. The punches extend through a stripper plate disposed below and spaced from the punch-carrying plate, and the punches are advanced against the work by a force-applying plate behind the punch-carrying plate. All of the above parts are assembled together with various supporting means and operating mechanisms.

It is essential that the punches be fastened solidly to the punch-carrying plate. Also, it is essential that the punches be readily removable from the plate as the punches are frequently broken in use. Broken punches must be replaced and the machine is rendered inoperative during the interval required for replacement.

Heretofore it has been necessary to remove a relatively large number of parts from the press in order to replace a broken punch, due primarily to the manner in which the punches are assembled on the punch-carrying plate. As a result it is necessary to shut the machine down for a considerable length of time each time a punch is broken. Such shutdowns are expensive, since neither the machine nor its operator earns anything during this time and a separate maintenance crew usually must be called in to service the machine. This complicated way of mounting the punches in the punch-carrying plate has been considered necessary heretofore in order to hold the punches solidly in place and to provide suflicient bearing surface to position the punch with requisite accuracy.

An important object of the present invention is to provide novel means for fastening punches to the punch-carrying plate so as to permit a broken punch to be replaced in a relatively short time.

Another object of the invention is to provide a novel punch-retaining assembly for presses of the above-mentioned character that makes it possible to replace a broken punch without disassembling large, heavy parts of the machine as here- I tofore required.

, Still another object of the invention is to provide a punch-retaining assembly that holds the punch attached solidly to the punch-carrying plate.

Yet another object of the invention is topic-- 2 vide a punch-retaining assembly which holds the pinch centered precisely on the punch-carrying p a e.

A further object of the invention is to provide a punch-retaining assembly having novel means for holding the punch properly positioned angularly about its axis.

Other objects and advantages of the invention will be apparent during the course of the following description.

- In the drawings forming a part of this specification and wherein like numerals are employed to designate like parts throughout the same:

Figure 1 is a view partly in section and partly in elevation showing a punch-retaining assembly embodying the invention;

Fig. 2 is a fragmentary, transverse sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is a view similar to Fig. 1, but showing a modified form of the invention;

Fig. 4 is a fragmentary, transverse sectional view taken on the line 44 of Fig. 3;

Fig. 5 is a view, partly in section and partly in elevation, showing still another modification of the invention;

Fig. 6 is a fragmentary, transverse sectional view taken on the line 66 of Fig. 5;

Fig. 7 is a view, partly in section and partly in elevation, showing yet another modification of the invention;

Fig. 8 is a fragmentary, transverse sectional view taken on the line 88 of Fig. 7;

Fig. 9 is a view, partly in section and partly in elevation, showing still another modification of the invention;

A Fig. 10 is a fragmentary, transverse sectional view taken on the line I 0-4 0 of Fig. 9;

Fig. 11 is a sectional view of structure, similar to that illustrated in Fig. 1, showing a still further form of the invention;

Fig. 12 is a view of structure, similar to that illustrated in Fig. 11, showing a further form thereof;

Fig. 13 is a sectional view of the structure illustrated in Fig. 11, taken on the line 13-] 3 thereof;

Fig. 14 is a sectional view of the structure illustrated in Fig. 11, taken on the line l4|4 thereof;

Fig. 15 is a view of structure, similar to that illustrated in Fig. 9, showing a further form which present invention comprises a retainer sleeve which is carried by the punch-carrying plate and is formed with a downwardly directed opening. This opening has an internally threaded portion and an accurately ground cylindrical portion below the internal threads. Also, a socket is provided in the opening behind the internal threads, which socket has an accurately ground, cylindrical surface. The punch is insertible upwardly into the opening of the sleeve, and the inner end of the punch has an accurately ground, cylindrical surface which fits snugly in the socket. Also, the punch is provided with a radial, downwardly directed shoulder which is disposed below the socket and behind the internal threads of the retainer sleeve. A look bushing fitting snugly around the punch is threaded into the retainer sleeve, and the inner end of the bushing seats against the radial shoulder of the punch to hold the latter solidly in the sleeve. The bushing must be removed from the sleeve whenever it isnecessary to re place a punch, and to this end the bushing is formed with wrench-engaging portion which projects from the sleeve. Also, the bushing is formed immediately behind the wrench-engaging portion with an accurately ground, cylindrical surface which enters and snugly fits the ground, cylindrical surface of the sleeve opening.

When the bushing is tightened against the radial shoulder of the punch, it holds the latter solidly in the retainer sleeve; and when the parts are so assembled, the interfitting, ground surfaces co-operate to hold the punch centered precisely in the punch-carrying plate. In the case of noncircular punches, suitable means also are provided for holding the punch positioned nonrotatably in the punch-retainer assembly so that the punch properly enters the female die.

For a more detailed description of the invention, reference is first had to the drawings and particularly to Figs. 1 and 2 which show a preferred embodiment of the invention. In the drawings the numeral iii designates the punchcarrying plate of a conventional punch press. This plate i9 is surmounted by a force-applying plate l2, and a stripper plate H3 is disposed therebelow and spaced therefrom. A punch 16 is carried by the plate iii and, as clearly shown in the drawings, the punch projects downwardly into an opening l8 in the stripper plate l6. Only one punch H is here shown, but it will be readily understood that the plate H3 may carry any desired number of punches. The shape of the punches and the location thereof on the plate IE! of course varies according to the particular shape and location of the holes to be made in the work (not shown).

As suggested, the instant invention is concerned substantially entirely with means for fastening the punch it to the plate It. According to the present invention, the punch-retaining assembly comprises a retainer sleeve 2i! disposed in and snugly fitting an opening 22 in the punchcarrying plate 88. At the upper end thereof, the sleeve 25 is formed with a radially enlarged head 24 which fits in a countersink 26 provided at the upper end of opening 22. The head 24 seats downwardly against an annular shoulder 28 at the juncture of opening 22 and countersink 25 and is held solidly against the shoulder by the force-applying plate 12. If necessary or desirable, the sleeve 20 may be provided with an external annular groove 35 at the juncture thereof with the head 24 to assure proper seating engagement between the head 24 and the shoulder 23.

The punch it here shown has an elongated, cylindrical shank formed with a reduced, cylindrical punching portion 34 at one end and a radially enlarged head 36 at the other end thereof. In so far as the present invention is concerned, it is significant to note that the head 35 is provided with an accurately ground, cylindricaL'peripheral surface which snugly fits the accurately ground, cylindrical wall of a socket 33 provided at the inner end of sleeve 20. These accurately ground, cylindrical surfaces cooperate to center the punch precisely in the sleeve 2%! and to hold the inner end of the punch l5 fixedly positioned. A cylindrical blank or spacer 49 is provided in the socket 353 behind the head 35 to have the ends of punches it of standard lengths disposed in different planes for punching holes in a workpiece having offset portions. The socket, sleeve, and bushing are lengthened to support the standard punches backed by the blank id of proper thickness, and in such arrangement like punches are employed in all the sleeves and bushings in the assembled punch plate.

In order to hold the punch It in the retainer sleeve 28, a locking bushing 32 is provided which fits snugly around the cylindrical shank portion of the punch and is threaded into the sleeve below the socket 3% At its inner end, the bushing 32 seats solidly against the head 36 to hold the parts assembled. In order to assure a proper seating engagement between the bushing s2 and the head 35, the punch 32 preferably is formed immediately below the head with a portion it of reduced diameter, The lower portion of bushing 42 extends downwardly from'the sleeve 25 and the projecting portion d5 thereof preferably is fashioned to provide wrench-receiving faces to assist in screwing the bushing into or from the sleeve 29. Immediately behind the wrenchengaging portion d6 of the bushing 42 is an accurately ground, annular surface 43 which snugly fits an accurately ground, internal, iannular surface as at the lower .end of sleeve 29. Also, the shank portion 32 of the punch 66 and the internal surface of bushing 42 are accurately ground to hold the punch solidly and precisely centered.

Upon the removal of the pressure plate It, the punch id can be easily removed from the plate it? merely by unscrewing the bushing 32. The sleeve 29 is prevented from turning during tightening or loosening of the bushing in any suitable manner as by means of apin 52at the interface between thehead 2d and the punch-carrying plate ii (Fig. 2). As soon as the external threads of the bushing t2 disengage the internal threads of sleeve 253, the bushing will drop down to entirely release the punch 86 and the latter then can be easily removed from the sleeve 28.

Conversely, to insert a new punch in the sleeve 20 it is necessary merely to assemble the bushing 42 on the punch and insert the assembled parts upwardly into the sleeve. The bushing 22 can be easily and quickly threaded into the sleeve 26 and when tightened it holds the punch solidly in place. The accurately ground annular surfaces hereinabove specifically referred to co-operate to hold the punch precisely centered in the plate it. Thus, after the removal of the pressure plate i only a few minutes is required to replace any punch on the plate In, and it is not necessary to remove or disassemble any other parts of the press proper in order to effect removal of a punch.

The form of the invention shown in Figs. 3 and 4 is primarily adapted and pro-eminently suited for use with punches which are made of expensive material such as tungsten carbide. It is not practical to make such punches in the form shown in Fig. 1, since in making the punch it must be trimmed down from the diameter of the head 36. In the case of hard materials such as tungsten carbide, this trimming operation would be exceedingly dimcult and the material removed would be wasted. Accordingly, in such cases I propose to use the construction shown in Figs. 3 and 4.

Except for the punch, the second form of the invention now described is identical to the form shown in Figs. 1 and 2. The punch 54 here shown is uniform in diameter throughout its length except for the reduced punching end 56 and an annular groove 58 adjacent the inner end thereof. This construction requires the removal of only a small amount of material to make the reduced punching end 56 and groove 58. A ring 66 is shrunk into groove 58 and the latter is positioned on the punch 54 so that the ring provides an annular shoulder on the sleeve 20 corresponding to the under surface of head 36 in the first form of the invention. In Figs. 3 and 4 the inner end of punch 54 is piloted snugly in the socket 38, and the other parts of the assembly cooperate in the manner d scribed to hold the punch properly centered in the punch plate H3.

The form of the invention shown in Figs. and 6 is primarily adapted for punches having noncircular punching ends. A punch 62 of this type is shown in the drawings. Manifestly, these punches must be properly positioned angularly or rotatably in the punch-carrying plate ill in order that the punching die will cooperate properly with the female die (not shown). Accordingly, the punch-retaining assembly shown in Figs. 5 and 6 is modified slightly from the form of the invention shown in Figs. 1 and 2 in order to assure proper angular positioning of the punch.

In the latter form of the invention a spacer blank 64 of modified construction is employed instead of the spacer blank M] as shown in the first form of the invention. The undersurface of spacer bank 64 is formed with a diametrical tongue 66 which enters and snugly fits a correspondingly shaped groove 68 in the top surface of the punch head 36. Also, the spacer blank {it is positioned angularly in the sleeve by a pin 10 at the interface between the blank and the sleeve (Fig. 6). Thus, in the form of the invention the pin l6 acurately positions the spacer blank 54 angularly within the sleeve 29, and the r spacer blank in turn determines the angular position of the punch 62 in the assembly. Except for the above, the form of the invention shown in Figs. 5 and 6 is identical to the form of the invention shown in Figs. 1 and 2 and it enjoys the same advantages insofar as accurate positioning of the punch and convenience in assembling and disassembling is concerned.

The form of the invention shown in Figs. '7 and 8 illustrates still another way of holding a punch in a predetermined angular position in the punchcarrying plate It. Except for the punch, this form of the invention is identical to the form shown in Figs. 1 and 2. The punch 72 here shown is formed with an integral, upward extension 74 on the head portion 'Hithereof. The extension M is noncircular in form; and, in the form of the invention shown, is essentially square (Fig. 8). Extension 14 enters and snugly fits a correspondingly shaped opening 18 in the inner end of sleeve 20. Manifestly, the extension 14 and opening 18 co-operate to hold the punch 12 in a predetermined, angular position in the punchcarrying plate ID. This maintains the alignment of the rectangular end 19 of the punch with the rectangular recess in the female die (not shown).

In connection with the foregoing it will be readily apparent that the extension 14 may have any desired outline which is noncircular in form. In the case of certain odd-shaped dies it may be necessary that the extension enter the opening in only one position of the die. If this is necessary the extension can be suitably shaped so that it enters the opening in only one position. Manifestly a number of shapes will accomplish this object.

The form of the invention shown in Figs. 9 and 10 is primarily adapted for situations where a plurality of individual punches must be mounted so closely together that they cannot be fastened separately to the plate i9. Two punches 89 and 82 are here shown. In this form of the invention the punches are mounted in a punch carrier as which is identical to the external shape of the punch I6 in the form of the invention first described and is held in the retainer sleeve 26 by bushing 42 in the same manner as the punch it. Also, the punches and 82 are identical in shape to the punch l6 as shown in Figs. 1 and 2. In the drawings, the punches 80 and 82 extend through properly located vertical openings 86 and 88 and the heads of the punches fit in suitable countersinks 9B and 92 at the upper ends of the opening. The carrier 84 is located angularly or rotatably in the sleeve 26 by an eccentrically positioned pin 94 which extends upwardly therefrom and into a socket 96 in the force-applying plate 12. The punches 80 and 82 here shown are circular in form and thus need not be positioned angularly in the carrier 84; however, if noncircular punches are employed they manifestly can be positioned angularly in the carrier in any suitable manner as by either of the two means shown in Figs. 5 and 7.

In view of the foregoing, it will be readily apparent that all of the punches in the gang can be removed simultaneously by merely unscrewing the lock bushing 42 and permitting the punch carrier 84 to drop out of the sleeve 20. Any or all of the punches associated with the carrier can be removed or replaced. Similarly, all of the punches in the gang can be fastened simultaneously in the plate Iii merely by inserting the carrier 84 and tightening lock bushing 42 against the shoulder defined by the head portion of the carrier.

In this form of the invention the sides of the punches are accurately ground and the bores 96 and 92 are also ground to snugly receive the punches so that the latter are solidly supported and accurately positioned.

Referring to Figs. 11 to 16 inclusive, a still further form of the invention is illustrated, that wherein the punch-retaining assembly is so constructed that a single length of punch may be utilized to service a press employing a plurality of punches which normally would be of different lengths. The assemblies are so constructed that even when the punches of standard length are ground to shorter lengths, the assembly may be adjusted to have the shorter lengths of punches projected further outwardly to be in the same '7 exception that it is of greater length having a longer internal ground surface Hi2 for-contact with the ground surface 13 of the bushing 164. As illustrated in'FigJl3, the sleeve W1 is secured against rotation to the plate illby a pin N15. The sleeve 15H has an enlarged internal recess H3? in which a separate plug W8 is provided so as to extend the endlil'ii of the punch ill outwardly from the face of the plate ill a greater amount than would occur if the punch were mounted on the plate without the use of the plug IE8. Between the recess 557 for receiving the plug its and the threaded portion N2 of the sleeve, a square opening H3 having rounded corners is broached or otherwise formed =in-the sleeve. The enlarged head I M of the punch H l is provided with four flat sides H connected by round corner-portions which mate with the fiat sides and rounded corners of the aperture H3 to prevent the punch iii from rotating, which prevention desirable when the end N9 of the punch is of a shape other than cylindrical. In view of the length of the aperture H3 and the ground surface 152, different lengths of plugs l-i may be provided between'the head lid of the punch and the plug 58, to thereby advance the end its outwardly from the face of the plate It is contemplated that a substantialamo'unt of the end its may be ground away at least to the dotted line ill and the bushing moved downwardiy with the punch the same amount as the plug i is is increased in thickness. The head i it of the punch may be provided with a threaded aperture 5 58 so that the plug 5 i5, having an aperture iii-3 therethrough, may be secured to the head by a screw extending through the aperture H9 and threaded into the aperture H8. Sun cient bearing surface will be provided at all times between the flat faces of the head i i l and those of the aperture 5 E3 and between the bushing and the surface 462 of the sleeve iii! to maintain accurate alignment and position for the punch l i i.

In Fig. 12 a similar assembly is illustrated, with the exception that the plug 598 is omitted so that the end of the punch l l i will be closer to the face of the plate ill than the punch in the assembly illustrated in Fig. 11, which amount will be equal to the length of the plug I98.

In Figs. 15 and 3.6, a similar assembly is illustrated for a gan of punches. rangement the punch carrier i2i has the head :22 provided with fiat sides H5 which mate with the flat sides of the square aperture H3 having the rounded corner portions located in the sleeve. A plug EH8 may be provided for initially locating the ends of the punches ill from the plate l5, and after the ends of the punches have been ground the plug 588 may be increased in thickuses the amount ground from the ends of the punches so that when they are again assembled on the plate iii, the ends of the punches will project the same distance from the face thereof.

In Fig. 16 the plug see is initially omitted so that the ends of the punches iii will project a standard distance frcrn the face of the plate i Q, and as the punches are ground off, a shim or plug may be inserted between the head E22 and the plate E2 of the press, as illustrated in Fig. 15, to have the ends of the punches disposed the same distance from the face of the plate. By employing the opening l l3 which is square or of any other polygonal or noncylindrical shape, the mating faces on the heads of the punches will remain in contact with the faces of the aperture as the punches and bushings are moved down- In this arr ward'ly due to the grinding and shortening of the punches. If a tonguelike 66 were relied upon for positioning the punch in the assembly, such a tong-us would become inoperable as the head of the punch is adjusted downwardly in the assembly. The flat engaging surfaces being longer than the amount of adjustment of the assembly, the complete adjustment thereof may be made and still have the punch or "punch carriers retained against rotation within the sleeve.

l-l-aving thus described the invention, I claim:

1. A punch-retaining assembly for punch presses of the type having a punch-carrying plate comprising a retainer sleeve capable of being supported by said punch-carrying plate and formed with an opening therethrough which is of reduced diameter near'the top end forming a socket which is accurately ground concentric to the opening, said opening having an internally threaded portion medially of the ends and an accurately ground cylindrical portion at the bottom end concentric with and of larger diameter than said threaded portion; a'punch in said retainer sleeve having a head portion in said socket and a ground shank portion in the opening below said socket, said head portion having an accurately ground, cylindrical, peripheral surface snugly fitting and guided by the ground, cylindrical surface of the socketto'hold the punch centered precisely in said sleeve; and a lock bushing fitting snugly but slidably on the shank portion of said punch and having an external thread threaded into the threaded portion of said opening, the inner end of said'bushing seating against the head of said punch to hold the latter solidly in the sleeve, said bushing having a wrench-engaging portion projecting from the sleeve and an accurately ground, cylindrical surface between said wrench-receiving portion and the thread snugly fitting and guided by the ground, cylindrical urface at said other end of the opening in the retainer sleeve for accurately aligning the punchwithin the sleeve and bushing in any position of longitudinal adjustment of the punch therein.

2. A punch-retaining assembly for punch presses of the type having a punch-carrying plate comprising a retainer sleeve adapted to be carried by said punch'carrying plate and formed with a downwardly directed opening extending completelytherethrough, aportion of said opening near the top end forming a'socket,fisaid opening having an internally threaded portion below said socket and an accurately ground,lcylindrical portion below said internal threaded 'portion'and said socket having an accurately ground, cylindrical surface; a punch in said retainer sleeve aving a head portion in and projecting from said socket and provided with a ground, cylindrical, peripheral surface snugly fitting and guided by the ground, cylindrical surface of the socket to hold the punch centered precisely in said sleeve; anda loci: bushing fitting snugly but slidably on said punch and threaded into said opening, the inner end of said bushing seating against the projecting head portion of said punch to hold the lat er solidiy' in the sleeve, said bushing having a wrench-engaging portion projecting from the sleeve and an accurately ground, cylindrical surface behind said wrench-reserving portion snugly fitting and guided by the ground, cylindrical surface of said opening to co-operate with said first-mentioned ground surfaces in holding the bushing and said punch centered precisely in the sleeve.

3. A punch-retaining assembly for punch presses of the type having a punch-carrying plate comprising a retainer sleeve adapted to be carried by said punch carrying plate and formed with a downwardly directed opening extending completely therethrough, a portion of said opening near the top end forming a socket, said opening having an internally threaded portion below said socket and an accurately ground, cylindrical portion below said internal threaded portion, and said socket having an accurately ground, cylindrical surface; means for holding said retainer sleeve against rotation relative to said punch-carrying plate; a punch in said retainer sleeve having a head portion'in and projecting from said socket and provided with a ground, cylindrical, peripheral surface snugly fitting and guided by the ground, cylindrical surface of the socket to hold the punch centered precisely in said sleeve; and a lock bushing fitting snugly but slidably on said punch and threaded into said opening, the inner end of said bushing seating against the projecting head portion of said punch to hold the latter solidly in the sleeve, said bushing having a wrench-engaging portion projecting from the sleeve and an accurately ground, cylindrical surface behind said wrench-receiving portion snugly fitting and guided by the ground, cylindrical surface of said opening to co-operate with said first mentioned ground surfaces in holding'the bushing and said punch centered precisely in the sleeve.

4. A punch-retaining assembly for punch presses of the type having a punch-carrying plate comprising a retainer sleeve adapted to be carried by said punch-carrying plate formed with a downwardly directed opening extending completely therethrough, the portion of the opening near the top end of the sleeve forming a socket, said opening having an internally threaded portion below said socket and an accurately ground, cylindrical portion below said internal threaded portion, and said socket having an accurately ground, cylindrical surface; a punch in said retainer sleeve having a head portion in and projecting from said socket and provided with the ground, cylindrical, peripheral surface snugly fitting and guided by the ground, cylindrical surface of the socket to hold the punch centered precisely in said sleeve; means for positively holding said punch angularly positioned in and against rotation relative to said retainer sleeve; and a lock bushing fitting snugly but slidably on said punch and threaded into said opening, the inner end of said bushing seating against the projecting head portion of said punch to hold the latter solidly in the sleeve, said bushing having a wrench-engaging portion projecting from the sleeve and an accurately ground, cylindrical surface behind said wrench-receiving portion snugly fitting and guided by the ground, cylindrical surface of said opening to co-operate with said first-mentioned ground surfaces in holding the bushing and said punch centered precisely in the sleeve.

5. A punch-retaining assembly for punch presses of the type having a punch-carrying plate comprising a retainer sleeve securable on said punch-carrying plate; a punch having an outwardly directed annular shoulder carried by said retainer sleeve; a lock bushing on the punch threaded into said retainer sleeve and hearing at the inner end thereof against said annular 10 shoulder to hold the punch solidly in the sleeve; and accurately ground cooperating surfaces on the retainer sleeve and the punch holding the latter positioned precisely in the sleeve against rotation while permitting longitudinal adjustment of the punch therewithin.

6. A punch-retaining assembly for punch presses of the type having a punch-carrying plate comprising a retainer sleeve securable against rotation on said punch-carrying plate; a punch having an outwardly directed annular'shoulder carried by said retainer sleeve; a lock bushing on the punch threaded into said retainer sleeve and bearing at the inner end thereof against said annular shoulder to hold the punch solidly in the sleeve; and accurately ground, cooperating surfaces on the sleeve and the body of the punch and on the sleeve and the bushing which holds said punch centered precisely in the sleeve and bushing in different positions of longitudinal adjustment of said bushing in said sleeve.

7. A punch-retaining assembly for punch presses of the type having a punch-carrying plate comprising a retainer sleeve, interengaging means adapted to secure said sleeve against rotation on said punch carrying plate; a punch having an outwardly directed annular shoulder carried by said retainer sleeve; a lock bushing on the punch threaded into said retainer sleeve and bearing at the inner end thereof against said annular shoulder to hold the punch solidly in the sleeve; accurately ground, cooperating surfaces on the retainer sleeve and the punch holding the latter positioned precisely in the sleeve along its axis while permitting longitudinal adjustment of the punch by adjusting the bushing in said sleeve, and means for holding said punch fixed against rotation in the sleeve.

3. A punch retainer comprising a sleeve having a polygonal aperture through the center thereof at one end, an internal thread medially of the ends and a ground cylindrical wall which extends to the opposite end of the sleeve; and a bushing having a hollow interior for receiving a punch and having an external thread at one end and a ground cylindrical surface at the other, the thread and surface of the bushing mating with the thread and surface of the interior aperture of the sleeve.

9. A punch retainer comprising a sleeve having a polygonal aperture through the center thereof at one end, an internal thread medially of the ends and a ground cylindrical wall which extends to the opposite end of the sleeve; and a bushing having a hollow interior for receiving a punch and having an external thread at one end and a ground cylindrical surface at the other, the thread and surface of the bushing mating with the thread and surface of the interior aperture of the sleeve, the bushing at the end having the thread being provided with an internal shoulder for receiving and supporting the head of a punch.

10. A punch retainer comprising a sleeve having a polygonal aperture through the center thereof at one end, an internal thread medially of the ends and a ground cylindrical wall which extends to the opposite end of the sleeve; and a bushing having a hollow interior for receiving a punch and having an external thread at one end and a ground cylindrical surface at the other, the thread and surface of the bushing mating with the thread and surface of the interior aperture of the sleeve, the end of the aperture opposite to that having the polygonal aperture being enlarged to form a recess for a plug for extending the. end, of title punch from the assembled sleeve and bushing 11. A punch. having a cylindrical body of pre-- determined diameter and having a projecting portion which constitutes the working end of the punch; and a head on the opposite end of the body portion of cylindrical form of larger diameter than the body portion, said head having four flat faces on; the. sides thereof conforming in dimension to the four fiat faces in the bore oia supporting sleeve with which the cylindrical head having the, four fiat faces mate.

1.2. A, punch having a cylindrical body of predetermined diameter and having a projecting portion which constitutesthe working end of the punchya head on the opposite end of; the body portion; of cylindrical form of lar er diameter than the. body portion and having four fiat faces on the sides, tl'iereof; conforming indirnension to the four fiat faces in the bore. of a supporting sleeve with; which the flat faces mate; said head having a tapped. hole onits outer end, a washerlike plug, and a screw for securing the plug on the end of the head.

13-. A punch-retaining assembly comprising a sleeve having a bore a portion of which at one end, is of a form for receiving an element; interengaging means between said sleeve and element adapted to positively prevent turning movement therebetween for accurately locating the element relative to the sleeve while permittingrelative 1ongitudinal movement. therebetween; a thread in the bore. wall adjacent;- to. said portion of predeter minediform. and an enlarged cylindrical surface at the oppositeend of the bore; and a bushing having an external threadon its upper end and a cylindrical surface on its lower end for engaging the thread and cylindrical surfaceof the sleeve, permitting a predetermined longitudinal adjustment therebetween while being retained in accurate axial alignment.

14. A punch-retaining assembly comprising a sleeve'having a bore therethrough one end of which. is of predetermined form for receiving the head of I a punch, interengaging means, between the head and sleeve adapted to positively'prevent relative rotating movement. therebetween. While permitting a degree of relative. longitudinal adjustment therebetween; the internal bore medially ofthe ends having an internal thread, the oppositev end having a cylindrical surface; and a bushing having an, externalthread on one end and acylindrical surface; on. the other which matewith the thread .and the cylindrical surface of the sleeve.

15.. A punch-retaining assembly comprising a sleeve having. a bore therethrough. one end of which is of predetermined form forreceiving th head of a punch for locating the. punch, interengaging means between the head. and sleev for positively preventing relative rotating movement therebetween while. permitting a degree of relativelongitudinal adjustment therebetween; the internal bore. medially of theends having an internalthread the opposite, end having acylindrical. surface; a bushing having an external thread on one end and a cylindrical surface at the otherwhich mate. with the thread and the cylindricalsurface. of the. sleeve, the thread and surfaces. being of such length as to permit the adjustment of the. bushing a predetermined amount fromthe sleeve without disengaging the thread or the mating surfaces; and a punch for said assembly having a cylindrical body portion which extends through a cylindrical bore through the bushing and having a punch portion on the one end and having. a head on the other end of such form as to mat with the portion of the bore of. the sleeve of predetermined form.

OTTO MUELLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED. STATES. PATENTS Number Name Date 143,473 Stephens Oct. 7, 1873 456,579 Long July 28, 1891 818,194 Richards Apr. 17, 1906 1,438,0 l0 Jones Dec. 5, 1922 1,507,783 Luce Sept. 9, 1924 1,790,444 Roberts Jan. 27, 1931 

